Parameter optimization of vacuum pulsed-infrared drying for honeysuckle extract: Bioactive retention and powder properties

Natural products are usually heat-sensitive, and the existing drying techniques generally have problems such as severe heat-sensitive degradation, high energy consumption and long time. On this basis, this study established the vacuum pulsed infrared drying (VP-IRD) technology for extracts and applied it to the drying of Lonicera japonica Thunb. (honeysuckle) extracts for the first time. Through systematic optimization of drying parameters (temperature 70°C, material thickness 6 mm, radiation distance 100 mm, vacuum time 10 min, atmospheric pressure time 4 min), high retention rates were achieved for chlorogenic acid (86.43 %), polysaccharides (85.76 %), and flavonoids (87.17 %). These rates represented a 9 %-12 % increase compared to hot air drying (HAD) and spray drying (SD), while consuming 75.73 % less energy than freeze drying (FD). Thermodynamic correlation analysis of VP-IRD revealed a strong positive correlation (r > 0.78) between the color parameter L* and the retention rate of active components, and a negative correlation (r = -0.63) between a* and the Maillard reaction, confirming L* as a sensitive indicator of component degradation during drying. Analysis of the physical parameters of the dried powder demonstrated that VP-IRD-treated powder possessed the optimal particle size distribution, significantly improved powder flowability and bulk density, and exhibited superior physical characteristics compared to HAD and SD. This study elucidated the synergistic mechanism of VP-IRD through a multi-scale analysis framework (active components - thermodynamic correlations - powder properties), providing an efficient, low-energy-consumption solution for the industrial drying of Chinese herbal medicine extracts that synergistically protects active components.